Why does food get stale over time?
James BeMiller, emeritus professor of food science at Purdue University, answers:
When we think of food going stale, we typically think of products such as bread. You might think that bread starts to stale days after it is made. But the process of staling actually begins as soon as the loaf leaves the oven and begins to cool. How quickly bread goes stale depends on what ingredients are in it, how it was baked, and the storage conditions.
Breads are essentially networks of wheat flour protein (gluten) molecules and starch molecules. Suspended inside this scaffolding are pockets of carbon dioxide gas that are produced during fermentation by yeast. This creates a foamlike texture.
The most important event in the process of staling is when starch molecules crystallize. The starch molecules need water molecules to form their crystal structure. They get the water molecules from the gluten. As a result, the network changes, becoming rigid at room temperature and below. This state, however, is reversed with the introduction of heat; stale bread can be freshened by warming it—as in toasting.
Although scientists have made considerable progress in dissecting the staling process, it remains poorly understood. Yet progress has been made in slowing staling through the addition of certain ingredients so that bread from large commercial bakeries in the U.S. seldom goes stale. On the other hand, the process of staling has also been sped up by other methods in order to make croutons in a relatively short time.
http://www.sciam.com/article.cfm?id=experts-why-does-food-get-stale
The Thermodynamics of Hell…
A thermodynamics professor had a quiz with one question: “Is hell
exothermic or endothermic?”
One student wrote the following:
First, if souls exist, then they must have some mass.
Next we must determine at what rate souls are moving into hell and at
what rate souls are leaving. We can safely assume that the forces that
brought them to hell will keep them there. Therefore, no souls are
leaving.
As for number of souls entering hell: Most religions state that if you
are not a member of their religion, you will automatically go to hell.
Since, people do not belong to more than one religion, we can
realistically project that all people and therefore all souls will go
to hell.
With birth and death rates staying as constants, we can expect the
number of souls in hell to increase exponentially.
Now, in regards to the rate of change in the volume of hell: Boyle’s
Law states that in order for the temperature and pressure in hell to
stay the same, the ratio of the mass of souls and volume needs to
remain constant.
So, if hell is expanding at a slower rate than the rate at which souls
enter hell, then the temperature and pressure in hell will increase
until all hell breaks loose.
Of course, if hell is expanding at a rate faster than the increase of
souls in hell, than the temperature and pressure will drop until hell
freezes over.
So which is it? If we accept the postulate given to me by Ms.Teresa
Banyan during my Freshman year— ‘that it will be a cold day in Hell
before I sleep with you.’ And take into account the fact that I still
have not succeeded in having sexual relations with her, then #2 cannot
be true, and thus I am sure that Hell is exothermic and will not
freeze.”
———————————————————————————————————————
He got an A+. No other person in the class passed.
Reining in manufacturing costs of fuel cell vehicles is the first major issue the automakers are addressing. While several have fuel cell prototype vehicles on the road—Toyota and Honda are even leasing them to the public in Japan and California—they are spending upwards of $1 million to produce each one due to the advanced technology involved and low production runs. Toyota hopes to reduce its costs per fuel cell vehicle to around $50,000 by 2015, which would make such cars economically viable in the marketplace. On this side of the Pacific, General Motors plans to sell hydrogen-powered vehicles in the U.S. by 2010.
Another problem is the lack of hydrogen refueling stations. Major oil companies have been loathe to set up hydrogen tanks at existing gas stations for many reasons ranging from safety to cost to lack of demand. But obviously the oil companies are also trying to keep customers interested in their highly profitable bread-and-butter, gasoline. A more likely scenario is what is emerging in California, where some 38 independent hydrogen fuel stations are located around the state as part of a network created by the non-profit California Fuel Cell Partnership, a consortium of automakers, state and federal agencies and other parties interested in furthering hydrogen fuel cell technologies.
The benefits of ditching fossil fuels for hydrogen are many, or course. Burning fossil fuels like coal, natural gas and oil to heat and cool our buildings and run our vehicles takes a heavy toll on the environment, contributing significantly to both local problems like elevated particulate levels and global ones like a warming climate. The only by-product of running a hydrogen-powered fuel cell is oxygen and a trickle of water, neither of which will cause any harm to human health or the environment.
But right now 95 percent of the hydrogen available in the U.S. is either extracted from fossil fuels or made using electrolytic processes powered by fossil fuels, thus negating any real emissions savings or reduction in fossil fuel usage. Only if renewable energy sources—solar, wind and others—can be harnessed to provide the energy to process hydrogen fuel can the dream of a truly clean hydrogen fuel be realized.
Stanford University researchers in 2005 assessed the environmental effects of three different hydrogen sources: coal, natural gas, and water electrolysis powered by wind. They concluded that we’d lower greenhouse gas emissions more by driving gasoline/electric hybrid cars than by driving fuel cell cars run on hydrogen from coal.
Hydrogen made using natural gas would fare a little bit better in terms of
pollution output, while making it from wind power would a slam-dunk for the
environment.”
http://www.sciam.com/article.cfm?id=can-hydrogen-replace-gas&sc=rss
The Briggs-Rauscher reaction is known as an oscillating chemical reaction. According to Wikipedia: “the freshly prepared colorless solution slowly turns an amber color, suddenly changing to a very dark blue. This slowly fades to colorless and the process repeats, about ten times in the most popular formulation, before ending as a dark blue liquid smelling strongly of iodine.” The reason this occurs is that the first reaction causes certain chemicals to be released in to the liquid, which then, in turn, spark a second reaction, and the process repeats itself until exhausted.
Thermite is aluminum powder and a metal oxide which produces an aluminothermic reaction known as a thermite reaction. It is not explosive, but it can create short bursts of extremely high temperature. A thermite reaction is initiated with some type of detonator and it can burn at temperatures of thousands of degrees. In the clip above we see an attempt to “cool” the thermite reaction by dumping it in a vat of liquid nitrogen.
When helium is cooled cooled to -271c, it reaches the lambda point. At this stage (as a liquid) it is known as Helium II. Hellium II is a superfluid. When it flows through even capillaries of 10−7 to 10−8-m widths it has no measurable viscosity. In addition, it will creep up a container (as it seeks out a warmer area) seemingly against the effects of gravity. Just watch the clip above and be amazed!
Sulfur Hexafluoride is a colorless, odorless, non-toxic and non-flammable gas. Because it is over 5 times denser than air, it is able to be poured in to open containers and light weight objects can float on it as if it were water. Another fun use for this harmless gas is through inhalation; when inhaled, it lowers the voice drastically. The reason that your voice is lowered when you inhale sulfur hexafluoride is that the weight of the gas slows the sound waves produced in your vocal tract to just under half the speed of the sound. Helium works in the opposite way.
Superabsorbent polymers (also known as hydrogels) are able to absorb extremely large amounts of liquid relative to its own mass. For this reason, they are used in the commercial production of diapers, and incontinence garments, and other fields requiring protection from water or liquids such as underground cabling.
Sodium acetate, when heated and cooled, becomes supersaturated in water. When it comes in contact with another object it re-crystalizes. This reaction also causes heat, and so this has a practical use in heat pads. Sodium acetate is also used as a preservative, and also gives salt and vinegar chips their distinctive taste. It is referred to in foods as E262 or sodium diacetate.
When a superconductor is cooled to below its transitional temperature, it becomes diamagnetic: this is when something is repulsed from a magnetic field rather than drawn in to it. This discovery by Meissner has lead to the concept of frictionless transportation, as an object could be “floated” along a track rather than “attached” to it by wheels.
Potassium Chlorate is a compound containing potassium, chlorine and oxygen. It is often used as a disinfectant and in fireworks and explosives. When potassium chlorate is heated to melting point, any item added to it will cause a rapid disintegration in the form of an explosion (as we see in the video above). The gas coming off the potassium chlorate is oxygen. Because of this, it is often used in airplanes, space stations, and submarines as a source for oxygen. A fire on the space station Mir was attributed to this substance.
Magnesium ignites easily and burns very brightly. In this experiment, you see magnesium ignited in a shell of dry ice – frozen carbon dioxide. Magnesium is able to burn in carbon dioxide and nitrogen. Because of its brilliant light, it was used in early photographic flashes, and it is still used in marine flares and fireworks.
Sodium is a highly combustible element and the addition of water can make it explode. In this video we see a drop of water added to a small piece of sodium in a flask filled with chlorine gas. The distinctive yellow color of the light emitted is due to sodium’s ‘D lines’ – this is often used in street lighting. This experiment produces a great deal of heat. When you combine sodium and chlorine, you get sodium chloride - common salt!
Dilemma: It’s a Friday night after a long week at work, and you just want to kick back, unwind, and get trashed. Problem is, your friends want to go to some posh bar downtown, and you have only a twenty on you. How in the world are you going to get drunk on twenty bucks at a bar that sells ten-dollar martinis?
Solution: Buy an energy drink at a liquor store and use it as a mixer.
Why this works: Energy drinks have caffeine in them, which causes your veins to expand, allowing the alcohol the beverages are mixed with to circulate faster. A lot of energy drinks also have an amino acid called taurine in them, which helps speed up your metabolism. This causes you to feel the effects of the alcohol faster than you would under normal circumstances.
U.S. Department of Agriculture (USDA) team with more than ten million U.S. dollars from candymaker Mars Inc. will analyze the more than 400 million parts of the cocoa genome, a process that could help battle crippling crop diseases and even lead to better tasting chocolate.
Fungal diseases are estimated to cost cocoa farmers an estimated 700 million
U.S. dollars annually.
The analysis will not only identify what traits make cocoa-producing cacao trees susceptible, but it also will give scientists—and candymakers—a better understanding of every aspect of cocoa, from the ability of the trees to sustain drought to the flavor of chocolate.
“Once we have the whole genome, they’ll be able to go in and look at all the
genes they’re interested in,” said Ray Schnell, a research geneticist with the USDA, referring to candymakers. “They’ll all be interested in flavor genes.”
*Crop Yields and Flavor Genes*
The project’s backers say the work could be a boon, especially to African farmers, who produce about 70 percent of the world’s cocoa.
By determining which breeds of cacao trees are most appropriate for a specific locale and most able to fend off disease and drought, farmers could increase crop yields.
Though the project is funded by Virginia-based Mars—the maker of M&Ms, nickers, and other fixtures in American chocolate—its findings will be made public.
Mars says there will be more information to examine than any one company could ever do alone and that the main reasons for cracking the genome are to combat cocoa pests and disease.
“For us, the fact that Hershey has similar information that every other chocolate company in the world has, that’s fine,” said Howard-Yana Shapiro, Mars’ global director of plant science, in a phone interview from Rome.
Shapiro said he did not expect improvements in yields from research would lead to larger overall cocoa crops. He said higher yields would allow farmers to devote some of their land to other lucrative crops.
Virtually no cocoa is produced in the U.S., but the USDA has an interest in the crop because so many domestically produced items (think raisins and almonds, for example) are used in chocolate products.
